Elsevier

Brain Research

Volume 514, Issue 2, 30 April 1990, Pages 206-218
Brain Research

Weight-bearing hindlimb stepping in treadmill-exercised adult spinal cats

https://doi.org/10.1016/0006-8993(90)91417-FGet rights and content

Abstract

Hindlimb locomotion on a motor-driven treadmill was studied in 5 cats spinalized at a low thoracic level as adults. Six months after surgery, the cats were anesthetized and implanted for electromyographic (EMG) and force recordings in hindlimb muscles. For the last 5 months of the spinalization period, the hindlimbs of each cat were exercised daily for 30 minutes on a treadmill. Data were collected during hindlimb locomotion on a treadmill across the entire range of speeds each cat could accommodate. All trials were filmed (100 frames/s) for kinematic analysis. EMG data were recorded from the soleus (Sol), medial gastrocnemius (MG), tibialis anterior (TA) and extensor digitorum longus (EDL). Forces were recorded in vivo from the Sol and MG tendons. All cats could sustain full weight-bearing stepping without the need for mechanical stimulation of the tail. Although the general stepping pattern of the spinal cats was remarkably similar to that of normal cats, several key differences were identified. Compared to normal cats, the adult spinal cats walked at a lower range of speeds and exhibited a longer swing phase duration. The Sol produced forces and displayed activation periods comparable to those observed in normal cats. The MG of adult spinal cats, however, produced lower forces and had a later onset of activation in comparison to normal cats. Each of the muscles in all spinal cats exhibited tremor during stepping. These results suggest that there were limitations in the activation levels of some hindlimb flexor and extensor muscles during treadmill locomotion. These data further suggest that, in normal cats, accommodation to treadmill speed is accomplished by modulating supraspinal input to the lumbar spinal cord while leaving many of the timing details to be regulated by lumbar spinal networks.

Reference (33)

  • BurkeR.E. et al.

    Physiological types and histochemical profiles in motor units of the cat gastrocnemius

    J. Physiol. (Lond.)

    (1973)
  • BurkeR.E. et al.

    Motor units in cat soleus muscle: physiological, histochemical and morphological characteristics

    J. Physiol. (Lond.)

    (1974)
  • EdgertonV.R. et al.

    Effects of treadmill exercise on hindlimb muscles of the spinal cat. Symposium on Spinal Cord Reconstruction

  • EidelbergE. et al.

    Stepping in chronic spinal cats

    Exp. Brain Res.

    (1980)
  • ForssbergH. et al.

    The locomotion of the low spinal cat. I. Coordination within a hindlimb

    Acta Physiol. Scand.

    (1980)
  • GoslowG.E. et al.

    The cat step cycle: hindlimb joint angles and muscle lengths during unrestrained locomotion

    J. Morphol.

    (1973)
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